1. Field of the Invention
This invention relates to paraffin wax baths used for theraphy, particularly paraffin wax baths used for dermatological theraphy and arthritic treatment.
2. Description of the Related Art
For the treatment of arthritis and for moisturizing their skin, people may use paraffin wax baths. Solid paraffin wax is melted in the paraffin wax bath and then a person places his or her hand or foot into the melted wax inside the paraffin wax bath. When the person removes the hand or foot from the paraffin wax bath, a coating of paraffin wax is left applied to the skin. This procedure can relieve arthritic pain and can also be used for moisturizing the skin on a person""s hand or foot.
An example of the related art can be found in U.S. Pat. No. 6,184,500 issued to Glucksman. The paraffin wax bath described therein is quite functional but is an expensive design. In particular Gluckman teaches side and base resistive heating elements 44 and 46 around and under the inner tub 14. This need for multiple resistive heating elements increases the cost of the article. Also, a resistive heating element requires a relatively expensive temperature control device to obtain consistent temperature control and to prevent the heating element from overheating. A resistive wire heating element does not provide for fast heating, is bulky and heavy. Additional circuitry is required to allow a resistive wire heating element to operate at more than one AC voltage level.
Accordingly, for these and other disadvantages of the prior art designs, there is a need in the art for a less expensive, functional paraffin wax bath.
It is an object of the present invention to provide a paraffin wax bath that provides all the functionality required while providing an economic alternative to resistance wire implementations. An object is to provide fast heating, self regulation with reliable consistent control, improved safety, and long life.
The present invention includes an integral plastic inner tub attached to an integral aluminum plate holder, each of which has a flat bottom and a sloped wall. A positive temperature coefficient heating element is attached to the flat bottom of the aluminum plate holder for self regulating to a preset temperature by automatically varying a wattage of the positive temperature coefficient heating element in order to maintain the positive temperature coefficient heating element at the preset temperature. Heat from the positive temperature coefficient heating element is transferred from the integral aluminum plate holder to the integral plastic inner tub via the flat bottoms and the sloped walls thereby melting any wax inside the integral plastic inner tub. An electrical resistance of the positive temperature coefficient heating element decreases as the temperature of the positive temperature coefficient heating element decreases as heat is drawn away from the positive temperature coefficient heating element thereby increasing the wattage of the positive temperature coefficient heating element. The electrical resistance of the positive temperature coefficient heating element increases as the temperature of the positive temperature coefficient heating element increases thereby decreasing the wattage of the positive temperature coefficient heating element. This temperature self regulation keeps the positive temperature coefficient heating element at the preset temperature.